Thickened lubricants



sets to form a hydrogel. The by-product sodium sulfate is washed out by the repeated washings with water. The continuous water phase in this hydrogel is then replaced by continued washing with alcohol until an alcogel is formed. In order to remove the liquid phase without avr collapse of the gel structure, the alcogel is placed in an autoclave which is then heated above the critical temperature of the alcohol and the pressure is allowed to increase to a point above the critical pressure of the alcohol. The vent valve is then opened and the alcohol allowed to escape. Under these conditions, the silica gel structure remains practically undisturbed and the liquid phase of the gel is replaced with air. The material is then reduced in particle size by blowing it through a series of pipes containing sharp bends with jets of compressed air. Santocel C has a secondary particle size of about 3 to 5 microns.

Santocel A is prepared as set forth for Santocel C up to the point of removal of the product from the autoclave. This material is run through a continuous heating chamber where it is heated for 1/2 hour to a temperature of about 1500 F. to eliminate the last traces of volatile material. lt is then broken down in a reductionizer or micronizer to a particle size of about f inch in diam eter. The solids content of the original hydrogel used in preparing Santocel C is approximately higher than that of Santocel A.

AR is a modiiication of A, differing only in that the material is reductionized to about the same particle size as C, approximately 3 to 5 microns in diameter.

ARD is a modication of AR, diifering only in that ARD is densiiied by extracting air under vacuum, and therefore has a smaller volume than AR.

AX is an A which has not been devolatilized.

CDv is a C which has been devolatilized as set forth for Santocel A. The Santocel is reductionized before being devolatilized.

CDvR 'differs slightly from CDV in that the CDvR has been devolatilized just after heating in the autoclave and then reductionized. It differs from CDv in that the latter is reductionized before being devolatilized.

yThe primary differences between the A and C series are as follows: A

1. The Cs are prepared from a sodium silicate solution containing 25% more silica than the As. general the As are lighter and composed of smaller particles than the Cs.

2. The As have undergone a devolatilization step in their preparation.

The following are the bulk densitiesof several of the preferred silica aerogels:k

Density, grams per rnl.

' In general, AR and ARD show superior gelling ability and the As in general are better than the Cs. aerogels which have been devolatilized generally have a higher gelling eiiiciency than the undevolatilized aerogels.

Other types of inorganic gelling agents which may be used include a Fumed Silica marketed by B. F. Goodrich Company. It is iinely divided and appears very much like an aerogel. It is made by a combustion or vaporization process, as a source of white carbon black for the rubber industry. The particles are several microns in size and porous in nature.

Another material is Linde- Silica Flour marketed by Linde Air Products Co. It is very similar in physical appearance to the silica aerogel. The particle size of the silica is purported to be 0.01 to 0.05 micron and to be manufactured by burning silicon tetrachlorideand collecting the combustion product on cool plates analogous to the production of carbon black. The'particles are thought to be aggregates or clusters ofpartilS lather than of sponge-like character.

Therefore, in'

Still another inorganic gelling agent known is Ludox silica from Du Pont, which is known as a silica sol, andT silica derivatives thereof. It has a particle size of the order of 0.01 to 0.03 micron.

In preparing thickened lubricants it is necessaryto retion.

No attempt is made to enumerate allof the inorganic gelling agents which will be suitable, nor to present examples of all of them since the novel aspects of the invention reside in water-proofing the lubricant rather than the use of novel gelling agents, per se.

The lubricating oil to be used in the process may have any lubricating viscosity. It may be raw oil, acid refined, or solvent refined, as required for the particular lubricating need.

The nature of the base oil has been found to make little difference in the relative consistencies of the thickened lubricants and conventionally (acid) refined oils produce, slightly thicker lubricants than solvent-retined oils. Excellent working stability is obtained regardless'of the type of the base oil. An increase inthe viscosity of the 'base oil, as might be expected, brings increased viscosity to the thickened lubricant, and minimizes bleeding. TheV change is relatively small and fairly linear. The viscosity of the oil does not affect the working stability of the lubricant.

The relative proportions of the inorganic gelling agent v and the oil will vary somewhat depending upon the de- Silica sired body in the thickened lubricant, the gelling ability of the inorganic gelling agent and the viscosity ofthe oil used. It has been noted, for instance, that with the Linde Silica Flour, the lubricants are somewhat harder, i. er., have a lower penetration than lubricants containing the same weight of SantoceL Lubricants made with low viscosity oils require asomewhat larger amount of the inorganic gelling agent to give a lubricant of the same penetration. The thickened lubricant may vary in consistency from the consistency of a slightly thickened oil to a solid or semi-solid of grease-like consistency. In

general, the amount of the inorganic gelling Vagent falls within the range of 5 to 20%, and in most cases would fall within the range of 7 to 12%.

f'l'he amount of the inorganic gelling agent, as might be expected, affects the consistency of the thickened lubricant in that an increase in its concentration brings a corresponding increase in consistency. The range is fairly linear and the amount of the gelling agent can be selected with relation to the consistency desired in view of the information in the following examples. While the difference is slight, the lubricants made with lower concentrations of gelling agent possess better working stability, while lubricants with larger amounts of gelling agent show slightly improved temperaturel susceptibility characteristics. The bleeding tendencies are decreased by increasing concentrations of the gelling agent.

In general, the properties of the thickened lubricants are remarkably independent of the composition variables and are not critical. The relativey concentration of the gelling agent effects the most significant alteration, particularly with regard to the iinal consistency of the prody Y' y This permits the manufacture of thickened lubriuct. cants having a wide variety of consistencies.

The alkyl alkylol imidazoline which is included to` render the thickened lubricant water resistant,"is waterinsoluble, oil-dispersible and surface active. The long chain alkyl group is generally recognized as imparting hydrophobic properties. The expression oil-dispersible" includes materials which are oil-soluble. In generahthe The composition is-madeisimply by mixing -the-inorganic gelling agent, .it-heoil:r andthe alkyljalkylol imidazoline in any order orrmannerso .that theimiaoline. comesy '5* into intimate contact withjthefinrganic gelling agent.

In one embodiment, Nthe `imidazoline-.is incorporated with the inorganic gelling agent, for;example,f-by'dissolvfY ing the imidazoline in a solvent, such as-pntanje, mixing it with the gelling agent, and then evprtrigffthe pentane. Such a treated gellingag'ent can be sold as an article of commerce, and dispersed in an oil when thelaero# gel grease is to be prepared. 1 t Y Generally, theV imidazoline" isf dispersed inthe oil and the inorganic xgfellingi 3agent acide therewith. Any simple mixing t l y. yjbe employed, and if desired'the mixture may be homogenized in a colloid mill, although this is unnecessary. K

The imidazoline must be uniformly distributed in theV composition or Fon th inorganic Jgel'lingiagent Forthisf reason the imidazoline is generallyf'ildi'sp'sib ble-or the equivalent-soluble: in some mediiifn, which permits its application tothe gelling agent.

While the invention is not to `tbe limited to any example, is contactedwith water, the water replaces` the oil in the gel id therrseparatels'f "lieoilf` Ifn'ac:

cordance with the invention,rthem1dazol1ne surface activity, becomes attached to the silia'andproj-V Lf-,ried out onrsamp'lespf the thickened lubricants., i In ac-,Y

lcordanewith thismtest' aV 2 x 2V in.st ain1ess lsteel'fplate tects it from being wt by the water.

The imidazolinenhcleus", since it possesses'k ca'rtionic,v character, is attracted;` tofthe t anionic silica particl'es; with A t L reto and mixedi lmany of Y theory or explanation,it, maybeof assistancein, understanding Y the same to explain'tha't theixfi'r'gan'ic glll'ig agent is f the result that the hydrophobic galkyl group ofith-e m1e cule projects outward. Since `@vater molecules farejjthusfY prevented from contacting ythe silica, the stabilizing gent,' -Y although less polarthanfwater,'fis not eluted. However,

1 0.78 :imidazoline `offptas'uselkhereinV is intended* to refer Atoljthe" cornpo-Y g entswhichre essential to the composition, namely, the

Y oil, the"in`organic gelling agent, andi the imidazolirle;v and the expression does notfexclude; other components fromA in gears, for cutting,jgrirrlin'g'5,etc".Y y Y v Thev ollowingV :examples illustrate. preferred embodiments of the invention. 'Ihickenedlubricants made `,with

imidazoline, and'ffor this reason Amine fO'fis used Y the examples to study theeifectiofotherjvar-,l. iab1es.

f Several alkyllliylol imidazolnes-.ofgthe invention in* v Y enz-918% lconcentrationl were incorporatedfinai,thickened t lubricant formed ,ffromig8%' silicafaerogel"(Santocel ARD). Y

YA rigorous testto "determine water"stabilityfwas-carJ was.v coated withsfini'fornr :layer of i the thickene lubri-l cantg; lfllow'i'ng whiclrfthe coated plate `wasl Aimrrlerse jh aerogel; 4for exanple,"fbrolreY .do'w'ny immediately p o the long chain alllzyl groups are bleophilic; Any mode of compounding the thickened lubricant which lpermits the imidazoline to come into contact with the inoif'ganicv gelling agent so 'as torprote'ct itinthis way, may be Vem-rl ployed.

The composition of :the inventionis'not lirhit'ed vto th'e' Y n usingoil, gelling agent, Vand imidazoline.y Any'of lthe materials conventionally added tei,V lubricants andglfeasesY may be included. The expression consisting essentially face, gel to bottomlit? was rated fbafdorxvnogwate -'st 'Y @emanan y'ofthe'lubricarlrsfwere? A Ae", ASTMg'r-eas pe'letrtion Vtestin accordance v Eltsinp No.

Additive Structure "Unworked f B llnpolypropyleno Y ubricaton, such materials'bemggforinstance,ghigh-polyf N, gmers tomodify vviscosity-or viscosityindexgvmaterials to Y imparttackiness, lubricating lsolids'slichgas graphite, jantii 1 voxidant additives, corrosion inhibitors of various types, (sulfur, additives to render thelubricantm'suitable for use Table l-Continued l Y ASTM Pens Example No. Additive Structure Additigeugyil Solu- Y Water Stability Y 1 Y it Y l v Unworked V60 5 do i No water stability; zas 25o complete sep. of oil f H2? (IEE: and Santocel. CH2-N N i Cr'lHss 5 H20 CH2 do No water stability; 248 254 i l complete sep. of oil C12HzsN N and Santocel.

\- CnHas A 7 alle oe, Partially s01ub1e. Bad semmai and ou 21'9 241 Y separate in A10 min- HN N utes.

( CuHrz r 8 E2C CH; Soluble Very goed 234 248 H O CHnCHz-N N i CuHaB 9 HIC-CH: Not Soluble Bad emulsicetion 207 249 l l and water separa- HN N tion of oil and Santocel.

f CilHss Y 10 Hdl) (13H: Soluble Very good 200 270 H 0 CHleHz-N N CxvHai 11 Hullom Partially soluble...v very pp0r;.-. zas 247 HN /N (I3 Y Tall oil HG residue i 12 me om soluble very good 23s 54v HOCHnCHz-N N i Tall oil HO residue 2 n 13 H2O CH2 do do 237 255 H 0 GHzCHn-N N 141 H2O (IH: do Good 234 Y 248 H O CHzGHz-N N Y GuHsa 1 A commercial hydroxyethyl heptadecenyl imidazoline, soldunder the trade name Amine "0 by the Alrose Chemical Co. 2 Derived by reaction of tall oil fatty acids with the oorrespondlng diamine, as set forth in the reaction at column 2.

the table above shows they are not as eiective at ele-Y vated temperatures.

The remaining examples" of 'the table are of imidaz' olines. Examples 3 and 4 show the hydroxyalkyl group must be on the l-nitrogen and that there must be both an alkylol and an alkyl group. Examples 5 and 6 show the importance of the alkylol group on the l-nitrogen; even though there is a proper alkyl group on the 2-carbon, these compounds are not effective.

A comparison of Examples 7, 9 and 1l with Examples stiibilizer.r f

Examples 13 and 14 also .are excellent additives; .Y ,1* In general, Table I shows that*.imidautolies 'lackingA zr'hydroxyzgrlkyl `grop-nthez1initogen nd/onan alkyl group on 'thea2ca'rbon ie irieiective,.whi1e imidazolin'es bearing' both these groups' arveryfeffective stilize'sL lthis haspbeen appreciated in the prior Vart becausei ofthe n y Y inorganic nature of the gellinfg agenti, t-heqfollowinianex-v 'trationfgtests usin hei=ASTM grease-gpenetrtion es amples are included in order to demonstrate jthatfthe Werefworkedfinccoi'dancezyy th,the@n1 tor^i`ze`l AS inclusion of the imidaolifdo'es not interferewith this worker fordiffer'ent'mimber Vof stmkesgand 4 eser impositions.wresubiectenwt-un er d pene-f property. The following Aexamples are typicaluend show Y indicpte'd inthefollovvpg tabl the temperature su sce tilf1ilityA olf-.various greases `and thickened lubricants. The high temperature susceptibilf I A index is obtained byAsnbt-racting `thepenet 'on gt ,77 F. fi'i'fhpeitff'j the penetra-fion at 150 o f u susceptibility index isobtained b'yl tractiiig the pein! tration at -4 F. from the-penetration at300 E and l dividing by :the penetration at 77 lF.l The:smaller the number in all instances, V-thebet-tei `the -temper-ature-fsusi ceptibility. y "A i exeli, w n abnit TABL Vn .T

l An isobntylene polymer sold by the EnjeyCompany, Inc., commonly usedirnbbzpptldhg Qea isosity I i 'l by Well-known 'ufti They havethe Yfollcming fthis'period'of'use'was'lgoodindgtht'theilbiint compositions and temperatl'ire susceptibility indexes: Vhad wear resisting properties beltte'rtimn thatof acom- Y ABLE HI- parable `unitfoperating on conventionalwheelbearing T y g g'reas'evGener'al appearancefofthe-feiect of the-lubrica t f Acion-hythenthickend hibricant -was @entirely satisfactoryf i y O Y gfieif 2: It' eb *L `needed iepi lii"1'g, *isis*would.belfI j Nature of Soap Percent l Index ImIeagew Y oi Soap Viscosity, Viscosity HighV VAverage 70.

,'SUS V)index Temp. TempiKAV of Paratac (an isobutylene polymer sold'by Enjay'Company, Inc.) which is commonly used in conventional grease formulations to cause the grease to adhere to the surface to be lubricated. i

Composition (a) was placed in the right front and left rear wheel bearings of a 1947 Mack -10*A tractor truck and composition (b) was used in the left front and right rear wheel bearings of the same truck. The truckwas run for a period of 27/2 months over a distance-of 21,870 miles and inspected. The bearing rollers appeared oily by visual observation indicating good lubrication. Composition (a) was somewhat thinner, but it adhered to the bearing and there was no evidence of deterioration of the composition. Composition (b) was unchanged, and there was no evidence of deterioration All of the bearings were in excellent condition indicating that the compositions functioned as satisfactory Wheel lubricants even under severe conditions. Y.

Example 33 A composition is made by mixing 5% of a silica aerogel (Santocel C) withr89.5% of an acid-relined oil having a viscosity of 300 SUS at 100 F. (300 Red Oil), 0.5% of Amine O as described in Example l, and 4% of Paratac as described in Example (b).

Example 34 A composition is made from 7.5% of a silica aerogel 4(Santocel C), 89.75% of 300 Red Oil, 0.75% of Amine O and 2% Paratac.

Example 35 A composition is made from 10% of a silica aerogel (Santocel C), 89% of 300 Red Oil and 1% of Amine 0.

Example 36 The main requisite for a lubricant for this type of wrench is that it be quite thin in order to keep the power loss from the drag of the lubricant as low as possible. The criteria of successful performance is an initial low torque reading and a continued low torque throughout the time of the test. The torque measurements were obtained with the wrench running free and represents the drag of the lubricant on the power output of the tool. The following table represents the initial torque, torque afterV two minutes and the torque after six minutes when the compositions of Examples 33 to 37 were tested in the' impact wrench as compared to two soap-base greases obtained on'the open market under the trade names of #2 Roller Bearing and Wringer Post which are recommended for this type of lubrication.

l Drops'to 1.6 after 30 seconds.

, Considering the initial torque and the torqueafter the wrench had run for various periods, the group4 of lubricants made in accordance with the invention as a whole, represent a marked improvement over the conventional greases of the prior art. 1

In order to determine further the lubricating properties of the composition, the composition of examples 33, 34, k36 and 37 were compared with the #ZRoller Bearing'. grease, in determining the horsepower loss due to grease drag on a 365 B. S. center exhaust impact wrench used in breaking bolts. f Six each of /S-ll and 374-10 bolts were used and all threads were lubricatedr 'with a standard thread lubricant. The time required to break these bolts wasprecorded in seconds and the average time was taken and converted into horsepower output. The results are shown in the folowing table: v

TABLE VI Horsepower Output of Tool Lubricant %-11 %10 Bolt Bolt Examples 38 to 50 The following imidazolines can be substituted for anyl of the imidazoiines in the greas'es ofthe preceding ex I amples with good results:

Example No Additive Structure 3s nur -CHQ` rio-(onnli-fNV N (I3 CinHsv 39 rio-on. n.0" on,

` oH-N\ /N' Hooz o/ (lli-:Has

4o Hao on,

HOCHzCHzCHi--N N v l CNH 41 'Hic Lvern HOCHZCH=CHCH2N Y N 42., H2O CHQ CHzCHaCH--CHa-N N CisH 4a H2O on.`

noemen-onde VN CirHu Example No. Additive Structure 44 B2C- CH2 Y Homme-N N Y 5 (I) CiuHas 45 H2O (11H2 HocH2oH2c=ooH2`N -Nu 19 v C nHza 46 HxC- CH2 15 HOCH=CHQCHCHN\ N Hs i C HHM 47 H20-CHI HOCHaCHaCHCHz-N N H t C Ci'llia:

48 Hrw-'om 25 HOCHi-N N t t dans t L Y 30 49 Evo-CH2 H2O CH;

CH-CH-N Nv v i Ilo-C; \C

v 14H2 35 5o H20-(IBB.

nooHlcHf-N v N i C t 11H21 40 This application is a continuation-impart of our apf plication Serial No. 119,752, led October 5, 1949, now abandoned. f t t We claim: 1 H* 45 l. A water-resistant thickened lubricant of good tem'- perature susceptibility properties consisting essentially of a mineral lubricating oil of lubricating viscosity, an amount of an inorganic gelling agent to impart a grease-` like consistency to the oil upon addition thereto, and V0 an oil-soluble, water-insoluble, surface active alkyl alkylol imidazoline having the formula v H20- CH2 Y.. s Y141" where'Ris `an alkylolfgroup and R isl selected from the group consisting of alkyl and alkylene groups,`said com@v pound being in an amountto impartfstab'ility against v deterioration by water.

y 2. A water-resistant thckenedlubricantrof good tenl-` perature susceptibility properties in, accordance with clairn 1, wherein Ris hydroxyethyl."k v g l v 3K. A water-resistant thickened lubricant kof good temperature susceptibility propertiesin accordance with claim i 1, wherein R is undecyl. f 1

4. A waterresistant'thickened lubricant Vofr good temperaturesusceptibility properties in accordance withlclairn u peraturesusceptibility propertie'sinl accordance with claim 7. A water-resistant thickenedlubrilcantof good teinperature susceptibility properties` inraccordance with claim 'i v l, whereinv the Yin'ridazolin'e is:v

r` 1 8.-,A water-resistant thickened'lnbricantfof Vgoodtern- `perature susceptibilityproperties in accordancezwith claim, r1, wherein theimidazoline is: I

H'oomcm-lN Nv Y t Y y i"frauilioresidueV Y t ,y '9. A water-'resistantthickened l'ubricantof` good temt perature susceptibility properties in accordance with claim Y 1, wherein `the irnidazoline y t 't Y if Hic-C133.

-t nooi-'rzorH-Nvk N i t y Y C. n Y NH3 t References Cited intlieileY of this patent ,K VUNITEDk STATES PATENTS 2,531,440Y p 2,554,222` Y Vstrass `-V Y May 22,1951

Jordan Nov. 2s, 195o 

1. A WATER-RESISTANT THICKENED LUBRICANT OF GOOD TEMPERATURE SUSCEPTIBILITY PROPERTIES CONSISTING ESSENTIALLY OF A MINERAL LUBRICATING OIL OF LUBRICATING VISCOSITY, AN AMOUNT OF AN INORGANIC GELLING AGENT TO IMPART A GREASELIKE CONSISTENCY TO THE OIL UPON ADDITION THERETO, AND AN OIL-SOLUBLE, WATER-INSOLUBLE, SURFACE ACTIVE ALKYL ALKYLOL IMIDAZOLINE HAVING THE FORMAULA 